Insider Voices Roundup: LG&E’s solar energy study and trade skills in high school

The recent article about LG&E using solar and energy storage to power Louisville solely by the sun is misleading.

The case study focuses on a small portion of the total LG&E Louisville service area that they call the Highland 1103 distribution circuit. The study says this is an “area that has approximately 1,600 residential customers and 240 commercial customers that use approximately 20,500 MWh annually and a summer peak demand of 8.9 MW.” The study also says “that in order to power this area with solar and energy storage alone it would take an area roughly the size of Cherokee Park and doing so would require a large geographic space that would result in land being used on a scale that would likely not be acceptable to the local community. And the cost of electricity would likely be two to five times higher over the 30-year study period as compared to continuing to take electricity from the LG&E system.”

There are three things wrong with that statement. First, the area required to produce 20,500 MWh per year with a solar array would be around 25 acres, and Cherokee Park is much larger at nearly 400 acres. Second, the notion that the solar array has to be located adjacent to the neighborhood and that it would be too costly to locate the solar array at a remote location is incorrect. And third, solar plus energy storage would be much cheaper than continuing to use the existing system. I’ll address the second and third points below.

The first, most logical option to power this area with solar and energy storage would be to install as many solar panels on the roofs of the houses in this neighborhood as possible. The most efficient place to produce power is at the same place it’s consumed. This option should also include installing battery banks (i.e., energy storage) in the houses, and this would be done for three reasons: provide backup power during grid power outages, lower the peak demand, thereby reducing stress on the grid, and allow the homes to use the electricity created by the solar panels at night or during cloudy days.

A quick glance at the average footprint of each house in this area is roughly 2,000 square feet. For this example let’s say each house has about 500 square feet of roof space that is usable for a solar array. At 1,600 houses that equals about 800,000 square feet. If you add the 240 commercial buildings, that could easily equal over 1,000,000 square feet (23 acres) of available roof space for solar panels. And that doesn’t include parking lots, which could also be covered in solar carports. 23 acres is enough space for a solar array to produce the required 20,500 MWh mentioned in the study.

An extension to this first option could be what is being done in Australia by Tesla. They are currently installing what’s called a Virtual Power Plant in South Australia, where solar panels and batteries will be installed at 50,000 homes to provide up to 250 megawatts of capacity – as much as a large gas turbine. Thus creating a network of home solar and battery systems working together to generate and store energy and feed energy into the grid. Energy from the installed home solar and battery system provides electricity for the house on which it is installed. Any energy generated by the system and not used by the household will be dispatched to the grid. The dispatched energy will be centrally controlled to support the needs of the grid, providing additional energy to the rest of the surrounding area when it is needed.

Since we don’t have the power to force homeowners to install solar on their houses, we need an alternative option. A second option would be to install a utility scale solar array (or multiple arrays at multiple locations) with energy storage outside of town and connect it to the existing electric grid that serves Louisville.

This array could be just outside of Louisville or could be miles away. A good place to start would be the LG&E Cane Run Generating Station. A quick look at Google Earth shows that the property appears to be about 175 acres and consists of coal ash ponds and surrounding open field. If you cover that property with solar panels and add energy storage you could power over 12,000 homes.

Of course, more research would need to be done to see if this would be feasible and we would need to determine if it’s possible for the coal ash ponds to be covered similar to the way an old landfill is covered in order to install the solar array.

An extension to this second option is installing the solar array miles away. Since solar panels produce DC power, it would make sense to use High Voltage DC (HVDC) transmission lines to dispatch the electricity from a distant solar array to the end user.

Additionally, for long-distance transmission, HVDC systems are generally less expensive and suffer lower electrical losses. The longest HVDC link in the world currently is 1,476 miles. HVDC transmission losses are quoted as less than 3% per 600 miles. In July 2016, ABB Group received a contract in China to build an ultrahigh-voltage direct-current (UHVDC) land link with 1100 kV voltage, 1,900 miles in length, and 12 GW of power, setting world records for highest voltage, longest distance, and largest transmission capacity.

In Kentucky, we have plenty of clear land that is readymade for solar, and it’s only a few hundred miles away from Louisville. There are 574,000 acres (897 square miles) of land in Kentucky that have been surface mined for coal and more than 293 mountains have been severely impacted or destroyed by coal mining.

Another extension to either of these options is microgrids. A microgrid is a local energy grid with control capability, which means it can disconnect from the traditional grid and operate autonomously. A micro-grid can have a small solar array plus energy storage that can power a neighborhood and provide battery backup power during a grid outage. The battery bank can be a large battery system that can power the neighborhood or smaller battery banks at each house. The micro-grid would be connected to the existing grid and could consist of a community solar array and/or roof-mounted solar panels.

All of this can be done in Kentucky. As I wrote in an article back in 2011, if we merely put solar panels on one-fifth of the already cleared land from mountaintop removal coal mining, we would supply all of the electricity needs for the entire Commonwealth of Kentucky. The remaining four-fifths could be used for energy storage and/or wind power. To power all of Louisville, we would only need to cover roughly 5% (35 square miles) of land already cleared by mountaintop removal mining.

Regarding the cost to install a solar panel system with energy storage that could power the Highland 1103 distribution circuit mentioned in the LG&E study, if my company was bidding on the project the price would be somewhere around $43 million. It would consist of an 11.5 MW solar array with a 100 MWh lithium-ion battery bank for energy storage. The solar array would include dual-axis tracking to allow the solar panels to tilt to a steeper angle in the winter to maximize the solar harvest and also tilt throughout the day to track the sun across the sky. This would reduce the required size of the solar array and energy storage. Additionally, it would be a microgrid and still connected to the main grid. This would allow it to draw power from the main grid during the few days in the winter when it’s too cloudy or snowy for the solar array to recharge the battery bank. This would also greatly reduce the total cost of the system.

Over a 25-year period the cost of electricity would be around $0.08/kWh. That’s cheaper than what LG&E is charging now at $0.09/kWh. Assuming energy prices increase 2% per year, the average LG&E price would be around $0.12/kWh over the next 25 years.

So, the Highland 1103 distribution circuit could pay $43 million for solar electricity over the next 25 years or it could pay LG&E $65 million. That’s a potential savings of $22 million that could be spent in the local economy instead.

If you extrapolate for all of Louisville and power the entire city with solar plus energy storage, you could put an additional $10 billion into the local economy over the next 25 years. This includes the cost to run HVDC transmission lines from mountaintop removal sites to Louisville. The estimated cost for HVDC transmission lines is somewhere around $2 million per mile.

Energy storage technology is ready today. Right now we are installing lithium-ion (lithium ferro phosphate) batteries for our solar customers. The batteries are non-hazardous and have a 10,000 cycle life. If cycled once per day, that could equal a 27 year life expectancy.

Note: the calculations in this article only apply to the electricity use for Louisville, it doesn’t include the natural gas usage for heating. In my opinion, as we transition to renewable energy it would make sense to go after the electric use first. Then over the next few decades we could replace the gas appliances with electric appliances and power them with solar. Dan Hofmann, president of RegenEn Solar

Limited scope?

The study seems to focus on a single dimension. I’ve read that single solutions usually fail because complex problems are multi-dimensional and have multiple causes. This is especially true in a complex environmental situation. The “real” solution will involve a synergistic combination of many approaches, including solar investment(s) by LG&E, tax incentives for residents and businesses to invest in their own relevant solutions – wind energy, storage options, etc. What if companies and/or residents could sell back energy they create themselves? Every little bit could help. Jon Foley

Mix it up

This study strikes me as an attempt to discourage actual progress toward weaning us off fossil fuels.

Obviously, any single source of electricity generation is going to have downfalls. Rather than showing the potential for solar to generate probably half of our energy needs, they instead put out a fever dream of a study that shows how hard it would be to go 100 percent solar, and then insinuate with their map that they’d have to raze Cherokee park to make way for panels.

Maybe we could also put out studies showing how to go 100 percent wind power — we’d have to put up windmills in everyone’s front yard along with mandates that everyone has to go outside and blow really hard every time the breeze dies down.

It is abundantly clear that we have to have a mix of different technologies to meet our energy needs. Studies about any single technology trying to meet those needs is just an attempt to discourage any work towards adopting that tech and is a waste of time. Matt Stone

Solar is a win for everyone

Our solar panels work at maximum capacity on the hottest days of the summer.

This is a big plus for LG&E and KU, because with the net metering I help them create surplus energy that they can sell outside their public service regulated area for way more …. whatever the market demand will pay. Remember Enron?

Unfortunately, the LG&E and KU publicity and advertising campaign inviting their customers to buy a solar panel in their new solar farm and receive a very convoluted credit was flat out misleading.

If you have a system and run their numbers, they are way overcharging for a customer to be a “good environmental citizen.”

The biggest downside of this approach, (to discourage private solar investments) and moving net metering to a wholesale refunds versus the current parity rate of retail to retail rate, is that people will not install their own systems.

This results in a “very discouraging payback period”… forget the investment. It means loss of revenue and fewer jobs for installers. Those with current systems will have no one to service and maintain their current equipment unless Public Sevice of Kentucky makes LG&E provide the service? Never happen! Mac McClure

Careers prepared for high school

Why does JCPS think they have found a new evolutionary way by offering trade skills in high schools?

An education textbook l studied in college in 1957 cited Ahrens Trade High School in Louisville as a national model for preparing high school graduates ready for apprenticeship careers in high-paying industry.

JCPS closed seven career education centers around 1993 to move training into high schools. Harlan Smith

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